Substituted and unsubstituted arylethylamines are chemical intermediates of commercial significance. They are used in the preparation of pharmacologically active compounds and, in some instances, are themselves pharmacologically active. For example, phenethylamine and p-hydroxyphenethylamine (Tyramine) have sympathomimetic (adrenergic) action. Tyramine is also a moiety in opiates, and is useful as an intermediate or substituent in the preparation of other physiologically active compounds or compositions. Tyramine hydrochloride is an important pharmaceutical intermediate used for the preparation of bezafibrate, an anticholesterol agent. Hydroxytyramine (dopamine) is a pharmacologically important neural inhibitory transmitter. It is the active ingredient in the pharmaceutical compounds, Dopastat and Intropin. It also represents the naturally occurring immediate precursor of norepinephrine.
Because of the importance of arylethylamines, accounts of their synthesis are well known. Some of them are: U.S. Pat. Nos. 1,995,709; 2,567,906; 2,505,645; 2,784,228; and 3,966,813; Journal of Medicinal Chemistry, vol. 25, p. 1442 (1982); J. Chem. Society, Vol. 95, p. 1127 (1909); J. Amer. Chem. Society, Vol. 55, p. 3389 (1933), and Hakko Kooaku Kaishi, Vol. 55(2), pp. 68-74 (1977).
U.S. Pat. No. 5,041,669 (assigned to Hoechst Celanese Corporation) describes the synthesis of arylethylamines from acetophenones. The acetophenones are first converted to .alpha.-oximino acetophenones which are then hydrogenated to arylethylamines.
Pending U.S. patent application No. 07/630,127, filed Dec. 19, 1990, now abandoned, describes the synthesis of arylethylamine hydrochlorides by hydrogenation reduction of .alpha.-oximino acetophenones in an aqueous reaction medium.
There is a continuing interest in identifying improved and cost effective methods to prepare arylethylamines, preferably from readily available materials or materials that may be produced readily and economically. For instance, synthesis of (.alpha.-halo-.alpha.-oximino)acetophenones is known. U.S. patent application, Ser. No. 07/801,999, filed Dec. 3, 1991, describes the synthesis of 4-hydroxy (.alpha.-chloro-.alpha.-oximino)acetophenone (N,4-dihydroxy-.alpha.-oxobenzene-ethanimidoyl chloride). Compounds like 4-hydroxy (.alpha.-chloro-.alpha.-oximino)acetophenone are known to yield aryl aminoethanol hydrochlorides on reduction with lithium aluminum hydride, according to H. Brachwitz, Zeitschrift fur Chemie. Vol. 14(7), 268 (1974).